1. Field of the Invention
The present invention relates to a return fuel cooling system for an LPI vehicle and a control method thereof, and more particularly, to a return fuel cooling system for an LPI vehicle for preventing pressure of a bombe from increasing by efficiently cooling LPG fuel returning from an engine and controlling flow of the returning LPG fuel according to an operation state of an air conditioning unit, and a control method thereof.
2. Description of Related Art
In general, a liquefied petroleum injection (LPI) engine means an engine driven by a mono-fuel method in which a fuel pump is installed inside a bombe, LPG fuel is liquefied at a high pressure (5 to 15 bar) by the fuel pump, and liquefied fuel is sprayed for each cylinder by using an injector, contrary to a mechanical LPG fuel method dependent on pressure of a bombe.
Since the LPI engine sprays liquefied fuel, a vaporizer and a mixer which are constituent components of a mixer type of LPG engine are not necessary, and includes a high pressure injector, a fuel pump installed in the bombe, a fuel supply line, an LPI dedicated electronic control unit (ECU), a regulator unit for adjusting fuel pressure, and the like.
The electronic control unit of the LPI engine receives input signals of various sensors to determine a state of the engine, and controls the fuel pump, the injector, and an ignition coil in order to achieve an optimum air-fuel ratio and improve engine performance.
Further, the electronic control unit of the LPI engine controls the fuel pump according to the amount of fuel demanded by the engine to supply liquefied fuel to the engine, and the LPI injector sequentially sprays the fuel for each cylinder to implement an optimum air-fuel ratio.
However, in a vehicle to which the LPI system in the related art is applied, high-temperature return fuel returns to the bombe from the engine, a phenomenon in which internal pressure of the bombe increases according to an increase in a temperature of the LPG fuel. Especially, when the internal pressure of the bombe is higher than charging pressure of a charging station, there is a problem in that the LPG fuel is not charged in the bombe.
Accordingly, it is necessary to install a separate fuel cooling apparatus in order to lower a temperature of the fuel returning from the engine, so that manufacturing and installation costs increase and there is a limit in securing an installation space inside a narrow engine room.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.